powerpc:Add support of SPL non-relocation

Current SPL code base has BSS section placed after reset_vector. This means
they have to relocate to use the global variables. This put an implicit
requirement of having SPL size = Memory/2.

To avoid relocation:
	- Move bss_section within SPL range
	- Modify relocate_code()

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
diff --git a/README b/README
index 017a13d..52283e2 100644
--- a/README
+++ b/README
@@ -3332,6 +3332,9 @@
 		continuing (the hardware starts execution after just
 		loading the first page rather than the full 4K).
 
+		CONFIG_SPL_SKIP_RELOCATE
+		Avoid SPL relocation
+
 		CONFIG_SPL_NAND_BASE
 		Include nand_base.c in the SPL.  Requires
 		CONFIG_SPL_NAND_DRIVERS.